Simplify code for loading file content into String

Change-Id: I80288d729be864db793fe1f368ff31df10784c01

src/main/java/com/googlesource/gerrit/plugins/messageoftheday/FileBasedMessageStore.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/messageoftheday/FileBasedMessageStore.java b/src/main/java/com/googlesource/gerrit/plugins/messageoftheday/FileBasedMessageStore.java
index faab456..765c2f8 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/messageoftheday/FileBasedMessageStore.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/messageoftheday/FileBasedMessageStore.java
@@ -73,7 +73,7 @@
 
   private String loadMessage(String id) {
     try {
-      return new String(Files.readAllBytes(dataDir.resolve(id + ".html")), UTF_8);
+      return Files.readString(dataDir.resolve(id + ".html"), UTF_8);
     } catch (IOException e1) {
       logger.atWarning().log("No HTML-file was found for message %s, no message will be shown", id);
       return null;